1. Field of the Invention
The present invention relates to an RFID (Radio Frequency IDentification) tag performing exchange of information with an external device without contact. Noted that the term “RFID tag”, as used herein, may be referred to as “RFID tag inlay” as an internal component (inlay) for the “RFID tag” among those skilled in the art. Alternatively, the “RFID tag” may be referred to as a “radio IC tag”. Further, the “RFID tag” also includes a non-contact IC card.
2. Description of the Related Art
In recent years, there have been proposed various types of RFID tags which exchange information with an external device in a non-contact manner by means of radio waves, as represented by a reader-writer. There is proposed a kind of the RFID tag which is constituted by mounting an antenna pattern and a circuit chip (IC chip) for radio communication on a base sheet consisting of aplastic, a paper and the like (see, for example, Japanese Patent Laid-Open No. 2000-311226, Japanese Patent Laid-Open No. 2000-200332, Japanese Patent Laid-Open No. 2001-351082). As for the RFID tag of this type, a using form is considered in which the RFID tag attached to an article and the like performs exchange of information about the article with an external device, thereby effecting identification of the article and the like.
FIG. 1 is a top view showing an example of an RFID tag.
The RFID tag 1 shown in FIG. 1 is constituted by an antenna 12 provided on a base 13 which consists of a sheet-like PET film and the like, and by a circuit chip 11 which is electrically connected to the antenna 12 by soldering and the like and which is secured to the base 13 with an adhesive.
The Circuit chip 11 constituting the RFID tag 1 is capable of performing radio communication and exchange of information with an external device via the antenna 12.
Here, FIG. 1 shows, as the antenna 12 of the RFID tag 1, an antenna having a shape extending from the circuit chip 11 placed in the center of the RFID tag to the both sides of the circuit chip. However, the antenna 12 is not limited to this type, and a loop-shaped antenna and antennas having other various shapes may be employed as the antenna 12.
FIG. 2 is a figure explaining a state on the occurrence of a problem in a conventional RFID tag. FIG. 3 shows an enlarged view showing a portion within a circle R shown in Part (B) of FIG. 2 and explaining the problem which occurs in the state shown in Part (B) of FIG. 2.
Noted that the antenna is not shown in FIG. 2, FIG. 3 and in each of figures hereafter explained.
Depending on the application of the RFID tag 1, in addition to the using form in which the RFID tag 1 is attached in the flat state as it is as shown in Part (A) of FIG. 2, the RFID tag 1 may be stuck to a curved surface so that bending force is applied to the RFID tag, as shown in Part (B) of FIG. 2.
When bending force is applied to the RFID tag 1 as shown in Part (B) of FIG. 2, the problem may arise that an adhesive 14 is peeled from a base 13, as a result of which the electrical connection between a circuit chip 11 and an antenna (not shown, see FIG. 1) is not maintained and thereby the communication function is obstructed.
FIG. 4 is a figure showing an example of a preventive measure against the peeling shown in FIG. 3.
In FIG. 4, a circuit chip 11 on a base 13 is sealed with a mold resin 15. When such sealing processing by means of the mold resin is applied, the flexural strength is improved, but the entire thickness is increased, which leads to a result going against the demand for the reduction in thickness and size.
In view of the above described circumstances, the present invention provides an RFID tag having significantly enhanced resistance to bending force with little increase in the thickness.